Patient-reported outcomes in clinical trials of inhaled asthma medications: systematic review and research needs

To assess the diversity, application, analysis and interpretation of patient-reported outcomes (PROs) in asthma clinical trials.

We critically appraised the use of asthma-specific PROs in 87 randomised controlled trials (RCTs) of inhaled asthma medications published during 1985–2006.

A total of 79 RCTs reported PROs, of which 78 (99%) assessed symptom scores and seven (9%) assessed asthma quality of life scores. Only eight (10%) used validated instruments and five (6%) provided clinical interpretation of scores. Due to heterogeneity in the reporting of symptom measures, it is not possible to determine how many discrete symptom assessment instruments have been used. Only 26 (33%) of the RCTs that measured symptom scores reported the scores for follow-up. Limited improvement occurred over time: fewer than 30% of the RCTs used validated PRO measures in any individual year.

Numerous validated PRO instruments are available but it is unclear why few are used in asthma clinical trials. Problems include poor reporting, and uncritical analysis and interpretation of PRO scores. Research needs include identifying and recommending a set of PROs for use in asthma clinical research and providing guidance for researchers on the application, analysis and interpretation of PRO measures in clinical trials.